wirlybird

Hi Guys i have a 233 formula that i use for fishing it has a 454 BBC MPI, BW gearbox and a TRS drive. what would be the best prop for economy?

The exhaust dosent pass through the prop if that makes any diffrence

sprink58

That's a big question with out a bit more info... specifically, what gear ratio are you running in the TRS? If it's the 1.34 (I think that's it) I would figure a 23" Mirage + for starters. If you are running at slow to moderate speeds in a bunch of rough water try a 21" Mirage +. Just remember that you can easily over rev that engine in a light 233 with a short prop like a 21"....but it would give you better acceleration up and over swells in the ocean.

A.O. Razor

Revolution 4 or Mirage+

Prop for 4500-4600 rpms. The Rev4 will give you better midrange efficiency with lower planning speed, better hole shot, but less top speed than the M+.

I thought all the TRS drives were 1.5 gears.

If you don't have any of the info that Sprinks mention along with current speed numbers ect.it's kinda difficult.

If you have a 1.5 gear the 23" is tha place to start and the 21" if you have the 1.34 gear. Both wll make you top out around 59-61 with slip 10-12% @ 4600 rpms. These numbers are somewhat of an guesstimation, but high 50's to 60 is about where you will be speed wise. If the mentioned pitches put you at higher or lower rpms, you should of course move up or down in pitch accordingly. The rpms to shoot for when running wot is 4500-4600.

wirlybird

sorry guys the BW gear box is a 1.1 and im unsure of what the TRS runs im not to keen to open her up as the parts are imposible to get.

i would like to cruise at approximatly 25 knots and game fish at 8 knots

bbladesprops

Let us know if you would like to test a Revolution 4. We have them in stock for testing for $45.
This way you can see the mid range improvements prior to purchasing.
Call us and we can go through the details.

Brett

A.O. Razor

Do you have the serial number for your drive? If so, you could call Merc and find out. That being said. Take Brett up on hes offer. When you don't have more info than you do, you will need to test, otherwise there is a pretty big risk you'll end up with the wrong pitch, so money very well spend.

wirlybird

Thanks for the offer brett but im in Australia so it makes it a bit hard.

I realise its a bit vauge information wise but there is little to no information on formulas in australia running TRS drives so every little bit helps

A.O. Razor there is no information on the leg anywhere it came to me with many parts missing and i have just had to guess and make my own parts up where possible.

Thanks for the info Guys

i may go with a 21" or 22" as top end speed isnt that important to me. My mrs would definatly need a toilet brake doing 50-60 knots.

Is there any diffrence between the performance of an alloy to a stainless prop?

A.O. Razor

The alu and SS props are worlds apart. It's like putting cheap all season tires up against a top of the line high performance summer tires. Honestly, alu props are best used for spare props. You won't see 60 knts though, maybe 60 mph.

It's been a while since I've been around the TRS, but is it possible to see the input shaft in the bilge between the tranny and transom assy on your boat? I know I've seen some setups where it was possible. If possible, put it in neutral, have someone turn the prop shaft 10 full revolutions and you count how many revolutions the input shaft turns. That will give you a very clear idea about your gear ratio. If you have a ratio below 1.5, go with the 21". If 1.5 or higher, 23"

wirlybird

Yeah i was a bit conserned runing so much HP through an alloy prop

Woops MPH good correction

I cant see the shaft at all from memory but i will have a dig around and see if there is a gap somewhere

bbladesprops

wirlybird,

1.5:1 was the standard gear set.
We did make a few others back in the day for race apps.

You will definately want to go to the SS propellers. There are many reasons to do so. Performance and longevity are some of the main reasons.

I love the built in rev limiter comment about your wife.
Tell her my wife has the same thought process.

Take care and have a blessed and Merrry Christmas!!

Brett